This invention relates generally to vacuum seal mechanisms and is particularly directed to a remote controlled vacuum joint closure mechanism for a noncircular vacuum duct.
Joint systems have various applications such as in the areas of hydraulic couplers, electrical connectors and vacuum connections. These joint systems generally provide isolation for a given component, material or property (vacuum) of the system as it extends between first and second locations, or structures, of the system. A mechanical joint, or coupling, typically has various components including seals, a support structure, a clamping arrangement, alignment devices, load isolation, a handling system for maintenance and replacement, and a leak test provision for a vacuum or coolant joint.
The configuration of joint systems varies with the applications and environments in which they are used. Special characteristics and properties require specialized configurations and components in the joint system. For example, remotely operable joint systems generally require the application of seal forces uniformly over the range of thermal cycles, structural loads and pressure variations for a specified operating lifetime as well as provision for remote operation and replacement, or repair, of joint system components. The environment of a nuclear fusion reactor places perhaps the most demanding requirements on a remotely controlled vacuum joint system.
The prior art discloses various types and configurations of vacuum couplings. One example of a vacuum connector is a conoseal joint comprised of a male and female flange and a frustoconical shaped gasket(s) which is maintained in position either by bolts, v-band couplings, or a threaded union. These joints are generally limited to a circular cross-sectional shape and only the "double seal" conoseal joint is specifically designed for remote handling. Fusable metal seals are sometimes used for remote vacuum applications. These connectors include a low melting point alloy which provides both a seal and clamping in this type of joint which includes heaters embedded in the alloy to uncouple the joint. This type of seal is generally limited to use in a horizontal position and the low melting point alloy may not be compatible with high vacuum system out-gassing requirements.
Another example of a vacuum connector is the Gamah metal seal coupling in which a metal seal is positioned between conical surfaces and which makes use of a single bolt actuator requiring a 90.degree. piping turn at the joint for remote applications. The Graylock Remote connector utilizes a trunion and drive screw mechanism which tightens and loosens the three piece clamping system around conical flanges. Components of the clamping system are mounted in a slotted backing plate and a ribbed delta-shaped metal seal ring is clamped between the flanges. The Transuranium Processing Facility disconnect coupler (Tru), developed at Oak Ridge National Laboratory for small liquid lines, includes process tubes at each end thereof provided with a ferrule. A single axial bolt draws the top clamp against the bottom casting, capturing the two tube ferrules and providing the sealing force. The Hanford Connector is similar in operation to a wheel puller and includes three jaws or hooks which slip under the shoulder of a male connector and, by tightening the operating screw, the female block and male flange are brought together. A single bolt is also used to clamp the Unibolt Coupling wherein locking tapered shelves are caused to rotate against each other in a wedging action by the single clamp bolt which exerts an axial sealing pressure on a metal seal ring.
The aforementioned connectors suffer from various limitations which severely restrict their use in hostile environments. For example, several of these vacuum connectors utilize elastomeric seals which are unable to withstand high levels of nuclear radiation, high temperatures, or the very high vacuum sealing requirements of a nuclear fusion reactor. In addition, these joint systems are limited to use with vacuum ducts having generally circular cross sections.
The present invention is intended to overcome the aforementioned limitations of the prior art by providing a noncircular vacuum joint closure mechanism capable of precise remote control and able to withstand high levels of nuclear radiation, high temperatures and high magnetic and electric fields while maintaining a very high vacuum seal.